1. Field of the Invention
The invention relates to a flashlight, more particularly to a flashlight with a tail cap switch.
2. Description of the Related Art
Referring to FIG. 1, a conventional flashlight 1 is shown to comprise a conductive barrel 11, a tail cap switch 12, a lamp unit 13 and a battery unit 14. The barrel 11 has a front end portion 111 and an externally threaded rear end portion 112 with a distal rear end face 113. The battery unit 14 has a first electrode and a second electrode opposite to the first electrode in a longitudinal direction. The lamp unit 14 includes a lamp having a first lamp terminal 132 connected electrically to the barrel 11, and a second lamp terminal 131 connected electrically to the first electrode of the battery unit 14.
The tail cap switch 12 is mounted threadedly on the rear end portion 111 of the barrel 11, and includes a tail cap member 121, a push button member 122 and a conductive biasing member 123. The tail cap member 121 has an end wall 1211 formed with a button hole 1210, and a tubular wall 1212 extending from a periphery of the end wall 1211 in the longitudinal direction.
The push button member 12 has an operating portion 1221 slidably extending through the buttonhole 1210, a conductive contact portion 1224 connected to the operating portion 1221 and disposed to confront the distal rear end face 113 of the barrel 11 in the longitudinal direction, and a tubular support 1222 extending from the conductive contact portion 1224 and slidably into the rear end portion 112 of the barrel 11.
The conductive biasing member 123 has a first biasing end for contacting electrically the second electrode of the battery unit 14, and a second biasing end disposed in the tubular support 1222 and electrically connected to the conductive contact portion 1224.
When the push button member 122 is not pressed and the tail cap member 121 is not thoroughly screwed on the barrel 11, the conductive biasing member 123 will bias the push button member 122 such that the conductive contact portion 1224 is spaced apart from the distal rear end face 113 of the barrel 11, thereby breaking electrical connection between the barrel 11 and the second electrode of the battery unit 14. On the other hand, when the push button member 122 is pressed or the tail cap member 121 is thoroughly screwed on the barrel 11 to the extent that the conductive contact portion 1224 abuts against the distal rear end face 113 of the barrel 11, electrical connection will be made between the barrel 11 and the second electrode of the battery unit 14.
The following are some of the drawbacks of the conventional flashlight 1:
1. When the tail cap switch 12 is removed, such as during replacement of the battery unit 14, the push button member 122 and the conductive biasing member 123 may fall out since there is no mechanism for preventing undesired removal of the same, thus resulting in inconvenience or even loss of components.
2. Accidental or unintentional pressing of the push button member 122 of the tail cap switch 12 will result in waste of battery power.
Therefore, the main object of the present invention is to provide a flashlight that can overcome the aforesaid drawbacks of the conventional flashlight.
Accordingly, a flashlight of this invention comprises:
a conductive barrel adapted to receive a battery unit therein, the barrel extending in a longitudinal direction and having a front end portion and an externally threaded rear end portion with a distal rear end face, the battery unit having a first electrode and a second electrode opposite to the first electrode in the longitudinal direction;
a lamp unit mounted in the front end portion, the lamp unit including a lamp having a first lamp terminal connected electrically to the barrel and a second lamp terminal adapted to be connected electrically to the first electrode; and
a tail cap switch mounted on the rear end portion of the barrel, the tail cap switch including
a tail cap member having an end wall and a tubular wall extending from a periphery of the end wall in the longitudinal direction, the end wall being formed with a button hole, the tubular wall having an inner wall surface formed with an internally threaded segment that is spaced apart from the end wall in the longitudinal direction and that cooperates with the end wall to form a contact receiving space, the internally threaded segment threadedly engaging the rear end portion of the barrel and forming an annular shoulder at a boundary with the contact receiving space,
a push button member having an operating portion slidably extending through the button hole, a conductive contact portion connected to the operating portion and extending into the contact receiving space, the conductive contact portion being disposed to confront the distal rear end face of the barrel in the longitudinal direction, and a tubular support extending from the conductive contact portion and slidably into the rear end portion of the barrel,
an insulator unit for preventing electrical connection between the conductive contact portion and the barrel via the tail cap member,
a conductive biasing member having a first biasing end adapted to contact electrically the second electrode of the battery unit, and a second biasing end disposed in the tubular support and electrically connected to the conductive contact portion, and
an annular contact blocking member made of an insulator material, disposed around the rear end portion of the barrel and within the contact receiving space, and abutting against the annular shoulder.
The tail cap member is adjustable relative to the barrel to one of a normally closed position, a normally open position, and a switch on/off position between the normally closed position and the normally open position.
When the tail cap member is at the normally closed position, the contact blocking member does not project rearwardly relative to the distal rear end face of the barrel, and the end wall of the tail cap member presses the conductive contact portion of the push button member to abut against the distal rear end face of the barrel and thus form a closed electrical circuit.
When the tail cap member is at the switch on/off position, the contact blocking member does not project rearwardly relative to the distal rear end face of the barrel, and the biasing member biases the push button member such that the conductive contact portion abuts against the end wall of the tail cap member and is spaced apart from the distal rear end face of the barrel to break electrical connection between the conductive contact portion and the barrel in a non-operated state of the push button member. The push button member is movable in the longitudinal direction against biasing action of the biasing member to abut the conductive contact portion against the distal rear end face of the barrel and make electrical connection therebetween when an external pressing force is applied on the operating portion.
When the tail cap member is at the normally open position, the contact blocking member is disposed to project rearwardly relative to the distal rear end face of the barrel so as to prevent the conductive contact portion of the push button member from abutting against the distal rear end face of the barrel.